The rebooted “It” earns the highest compliment for a horror movie: Even if it didn’t have the homicidal clown and sink spewing blood and missing children getting yanked into sewers, what remains would still be an engaging movie. It’s smart and funny and makes great effort to capture not just a time and place, but the specific feelings of being on the verge of adulthood and thinking the world is against you. There are questionable structural differences between this film and Stephen King’s literary source material, and those will be particularly noticeable to fans of the 1990 television miniseries.